1. Field of the Invention
The present invention relates generally to marking movie film with information, more specifically to a unique method and apparatus for supplying a code to the movie film at the edge of each frame.
2. Description of the Prior Art
In the field of high-speed motion picture photography of ordnance rounds, it is desirable to have an identification code for each frame. An identification system previously used was a square panel with 16 lamps on it representing four binary coded decimals (BCD) digits. The panel has the disadvantage of having to be placed directly in the impact area so that it would be in the photographic field of view when used at a field test in which the camera's telescopic lenses were positioned in a tower overlooking the impact area. Prior art devices were developed to move the identification code or number generating system from the impact area to the camera position using an IRIG serial timing code generator to drive one of the two timing lamps already built into the camera by the manufacturer. The data rate of the IRIG code was not compatible with the camera film rate. Consequently, systems of the prior art would generally record the sequential bits and digits of the code over a plurality of frame edges. Other prior art devices, as illustrated in FIG. 2, would use four parallel markings to represent the four bits of a single BCD digit which, as in the previously discussed art devices, extends over a plurality of frames for each digit.
Other systems of information coding have tried to duplicate the concept of the original light panels wherein the digits are in sequence, but the four bits of the element are in parallel. This is illustrated in FIG. 1 wherein six digits of binary coded decimals are recorded for a specific frame. The systems of the prior art have recorded the digits by sequential exposures or have recorded the total digits by a single exposure at the edge of the film at the film gate, thus requiring synchronization with the shutter.
By use of long codes extended over many frames of the film, the identification or time code cannot be read while the original film frame is being interpreted. The film generally must be removed from he film projector and placed on a special device in order to read the code. Code readers of the prior device are generally optical readers or light tables. It is also extremely difficult to tell what portions of the code sequence you are in when the code extends over several feet of film. Thus, there exists a need for a coded sequence which will be recorded on the edge of a single frame and which is easily and quickly discernible to read.